Single main.R regardless of number of I.C.

[rabutler]

In #26, we added a second main file which will work for a normal set of CRSS runs. The code should work for any combination of the number of I.C.

Create one main.R file that will work for any set of I.C. and scenario comparisons:

• [x] 1 'normal' run, e.g., January 2016
• [x] 1 multi-initial condition run, e.g., April 2016
• [x] comparing normal run to multi initial condition run, e.g., compare January 2016 to April 2016
• [x] comparing two normal runs, e.g., January 2016 vs. January 2016 w/ 2017 start year
• [x] comparing two multi initial condition runs, e.g., April 2016 vs. June 2015

[rabutler]

main.R in v1.3 can handle all of these combinations